Advances in computing, wireless transceivers, displays, data input devices, batteries, materials and mechanics have promoted the miniaturization and weight reduction of wireless communication devices such as portable radiotelephones. However, there are tradeoffs associated with the advantages of such miniaturization.
Firstly, smaller devices result in a shorter distance between the earpiece and microphone transducers. Since the typical distance between a human ear and mouth remains unchanged, acceptable acoustic coupling between the earpiece transducer and the human ear, and between the microphone transducer and the human mouth is becoming more difficult to maintain. Various solutions have addressed this problem by slidably or rotatably coupling one or more moveable housing elements to the main body portion of the radiotelephone. The housing elements have earpiece or microphone transducers disposed therein. The distance between the earpiece and microphone transducers is increased by moving the housing element to an open position during use and decreased by moving the housing element to a closed position when not in use. Thus, reliable acoustic coupling is achieved when the radiotelephone is in use without compromising miniaturization when the radiotelephone is not in use. Examples of these solutions are shown in U.S. Pat. Nos.: D297,735, D297,734, D326,091, D326,451, D326,452, D298,244, D305,427, D300,827, D300,742, D304,189 and D297,736. However, as the devices become even smaller, the distance between the earpiece and microphone becomes even shorter and the acceptable acoustic coupling is even more difficult to maintain.
Secondly, smaller devices have less space for display and data input devices, such as keypads. The smaller devices have compromised these functions by making display characters and input keys smaller and thus harder to use. Additionally, the market for advanced communication devices is requiring more capability from the display and data input devices which is contradictory to the trend of providing less capability for the sake of miniaturization.
Thirdly, smaller devices have less space for an antenna thereby degrading transmission and/or reception performance. Smaller devices, having smaller antennas, are more susceptible to the well known shadowing phenomenon produced by the position of the human head between the communication device and the nearest base site when the device is held against the head during use.
Thus, there is a need to maintain acceptable acoustic coupling, increase display and data input device capability and increase antenna performance to encourage further miniaturization of wireless communication devices.